PMID:2843517
| Citation |
DiGate, RJ and Marians, KJ (1988) Identification of a potent decatenating enzyme from Escherichia coli. J. Biol. Chem. 263:13366-73 |
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| Abstract |
A topoisomerase has been purified from extracts of a topoisomerase I-deficient strain of Escherichia coli based solely on its ability to segregate pBR322 DNA replication intermediates in vitro. This enzyme rapidly decatenated multiply linked form II:form II DNA dimers to form II DNA, provided that the DNA substrate contained single-stranded regions. Efficient relaxation of negatively supercoiled DNA was observed when reaction mixtures were incubated at 52 degrees C, but not at 30 degrees C (the temperature at which decatenation was readily observed). This topoisomerase was insensitive to the DNA gyrase inhibitor norfloxacin and unaffected by antibody directed against topoisomerase I. Relaxation of a unique plasmid topoisomer revealed that this decatenase changed the linking number of the DNA in steps of one and was therefore a type 1 topoisomerase. The cleavage pattern of a fragment of single-stranded phi X174 DNA generated by this decatenase was virtually identical to that reported for topoisomerase III, the least characterized topoisomerase present in E. coli. |
| Links | |
| Keywords |
Chromosome Deletion; DNA/metabolism; DNA Replication/drug effects; DNA Topoisomerases, Type I/analysis; Escherichia coli/enzymology; Isoenzymes/analysis; Norfloxacin/pharmacology; Topoisomerase II Inhibitors |
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